Try source-native download, OA repositories, Unpaywall, then optional Sci-Hub. Args: source: Source name (arxiv, biorxiv, medrxiv, iacr, semantic, crossref, pubmed, pmc, core, europepmc, citeseerx, doaj, base, zenodo, hal, ssrn). paper_id: Source-native paper identifier. doi: Optional DOI used fo...
AI agents call download_with_fallback to retrieve information from Paper Search MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool is a Read operation as it retrieves data (academic papers) from multiple sources with no side effects beyond downloading and storing files locally. It queries repositories and fetches publicly available or open-access content.
From the tool's definition Tool performs download operations from academic paper repositories (arXiv, PubMed, bioRxiv, Sci-Hub, etc.) to retrieve and save published papers.
Documented attack patterns abuse exactly the kind of access download_with_fallback gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Paper Search MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for download_with_fallback:
{
"version": "1",
"default": "deny",
"tools": {
"download_with_fallback": {}
}
}download_with_fallback is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Try source-native download, OA repositories, Unpaywall, then optional Sci-Hub. Args: source: Source name (arxiv, biorxiv, medrxiv, iacr, semantic, crossref, pubmed, pmc, core, europepmc, citeseerx, doaj, base, zenodo, hal, ssrn). paper_id: Source-native paper identifier. doi: Optional DOI used for repository/unpaywall/Sci-Hub fallback. title: Optional title used for repository/Sci-Hub fallback when DOI is unavailable. save_path: Directory to save downloaded files. use_scihub: Whether to fallback to Sci-Hub after OA attempts fail. scihub_base_url: Sci-Hub mirror URL for fallback. Returns: Download path on success or explanatory error message. It is categorised as a Read tool in the Paper Search MCP MCP Server, which means it retrieves data without modifying state.
Register the Paper Search MCP server in PolicyLayer and add a rule for download_with_fallback: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Paper Search MCP. Nothing to install.
download_with_fallback is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the download_with_fallback rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for download_with_fallback. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
download_with_fallback is provided by the Paper Search MCP server (openags/paper-search-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 63 Paper Search MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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63 Paper Search MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.